GINGLYMACONCHA. UNIONIDZ. 323 
excellent pearls, which are often sent to India, and reimported 
as oriental pearls. There was formerly a pearl fishery in the 
Tay, and there is one at present in North Wales, which is said 
to produce a very considerable revenue to the proprietor, who, 
I have been told, is a female. 
I have adopted Lamarck’s specific name as more appropriate, 
as it is certainly longer than any other species, and all of them 
bear pearls. 
Genus 61. Unto. 
Unio, Bruguiere, Lamarck, Cuvier, Say, Rafinesque. 
Shells moderately thick, ovate, acuminated behind; the 
hinge with a short, lamelliform, cardinal tooth in each valve, 
wrinkled, or with many notches behind; in the right valve, 
under the cardinal ligament, is an elongated lamella; in the 
left are two elongated ligaments, which receive the right lamella 
between them ; the epidermis thin ; the hinder muscular im- 
pression compound. _ 
The orbicular muscles of the Hvis join each other behind 
the posterior adductor muscle and above the anterior adductor ; 
the branchiz are unequal; the outer ones, which are the 
smallest, are jomed even to their posterior extremities with the 
orbicular muscles, forming the superior respiratory or tracheal 
tube perfect; the abdomen is covered by a membrane ; the 
foot is acutely lamelliform. 
1, Unto OVALIS. 
Shells with their valves oval, the cardinal teeth wrinkled, 
the right one compressed, the left one with its apex notched ; 
the anterior lacinia excavated beneath, receiving the right one ; 
the epidermis pale fuscous luteous, radiated with luteous-green- 
ish, fuscous or black. Length four inches; height two inches. 
Mya ovalis, Lister, Anim. Angl. App. f. 6 ; Conch. t. exlvii. 
f.2; Donov. Brit. Shells, t. exxii. f. 1, 3; Flem. Edinb. 
Encycl. vii. 87. 
Mya ovata, Mont. Test. Brit. 31,563; M. & R. Trans. Linn. 
